Logic
by Colourcubify
Summary: Spock finds no logic in Carol Marcus being aboard the Enterprise. Truly, the only logical thing to do is to prove to Captain Kirk that there is no need for anyone else in Spock's position. Contains slight Into Darkness spoilers. Spock/Kirk smut. Mostly Dom!Spock. Two-shot. Enjoy!
1. Part 1

**AN: Soooo, I've been kind of obsessed with the new Star Trek movie recently, so here is some Spock/Kirk smut. It may be multi chapter when I feel like writing some pwp. At any rate, enjoy yourselves! I also have this posted on Ao3.**

* * *

"Captain Kirk?" an unfamiliar voice began, pulling Kirk's attention away from his First Officer. Spock's mouth tightened, displaying his annoyance at the interruption. "Science Officer Wallace. I've been assigned to the Enterprise by Admiral Marcus, " the blonde chirped, batting her made-up lashes at Kirk. Spock narrowed his eyes slightly, fist clenching unnoticed on the arm of the seat.

"You requested an additional Science Officer, Captain?" he asked sharply, gaze darting to Kirk, who had yet to look away from the buxom blonde. Spock's insides boiled, though nothing escaped to his face. 'This must be a mistake,' the Vulcan decided, 'There is no logical reason for the Captain to instate a second Science Officer.'

"I wish I had," Kirk replied, finally tearing his gaze away from the woman to send a crooked smile to his First Officer. Despite his rolling jealousy, the Vulcan was soothed minutely by the grin; that specific smile that his Captain saved only for him. "Lieutenant Carol Wallace," Kirk continued, reading off the pad the woman had given him, "Doctorate in Applied Physics, specializing in...advanced weaponry."

"Impressive credentials," Spock cut in, eyes shooting daggers at the officer. Ignoring her quiet 'thank you', he turned back to Kirk and commented, "A bit redundant, now that I'm back aboard the Enterprise,"

"And yet, the more the merrier," Jim cut in, exasperated. Spock lowered his eyes from the Captain's face, lest he see the emotion in the Vulcan's expression. "Have a seat, doctor."

With a second whispered thanks, the girl took the only seat left in the pod: the one between Spock and Kirk. It was only logical, yet at the moment, logic was pushed to the back of the First Officer's mind. He wanted this new officer gone. The Enterprise didn't need her, because they had Spock. Staring past the blonde woman, Spock tried to catch Kirk's eye, but was ignored. Turning back to the window to his left, the Vulcan sat silently for the remainder of the trip.

* * *

"Captain, may I speak to you in private?" Spock asked quietly, standing stiffly next to the Captain's chair. Kirk turned to him, surprised, then nodded assent. Ignoring the knowing glance Sulu sent them, the Vulcan led Jim out of the bridge and through the hallways of the Enterprise. Spock could almost hear his Captain's curiosity leaking from him as he followed through the ship. It was only logical, of course, that he would be wondering at Spock's intentions, what with him leading the blonde man towards the crew quarters of the ship.

Reaching his own room, the First Officer opened the door, gesturing for Jim to enter first. Cocking an eyebrow in amusement and bewilderment, the Captain obeyed. As he passed close to the Vulcan, Spock breathed deeply, inhaling the scent that was indescribable, but that was Kirk's alone. His eyes fluttered closed unknowingly for a moment, only to snap open at the sound of his Captain's laughter as he poked around his First Officer's room. Stepping into the room and allowing the door to close, Spock straightened his back, clasping his sweating hands behind it. It was only logical that the human part of him were displaying physical signs of his nervousness, but he disliked it immensely.

"So..." Kirk began, breaking the silence that was beginning to become awkward. Spock swallowed, nodded firmly to himself, and locked eyes with his Captain.

"Captain, I..." he trailed off, unsure how to even begin what he wished to convey to his superior.

"Is this when you're apologizing about the volcano?" Kirk guessed, leaning onto the Vulcan's bed, "Because you don't have to, Spock. I think Uhura is more upset than I am, anyway,"

"No, Captain, though I am...sorry, about that. I will try to take others' feelings into consideration in the future,"

"Then what is it?"

"I can't say, Captain,"

Kirk laughed, confused.

"What do you mean, Spock? You can tell me anything,"

Shaking his head, the dark haired man strode purposefully across the room till he was standing before his Captain. Raising one hand to Kirk's face, Spock touched it lightly, watching his eyes to gauge a reaction, rather than melding with his mind as he would have normally. He had the feeling his Captain would not appreciate the action.

"I believe that it is logical that I show you instead," the Vulcan stated, tracing the tips of his fingers down the blonde's cheek to cup his chin. "Jim?" he whispered, mouth inches away from the other man's.

"Yes, Spock?" He had never heard his Captain sound so breathy. A slight smile graced the brunette's lips as he descended. Hovering right above Kirk's lips he spoke again.

"Do you want me?"

Jim responded by taking the man's free hand and pressing it to his bulging crotch.

"It's only logical what you should do, pointy," he teased, grinding into the hand, the crooked grin covering his face.

Wasting no more time, Spock pressed his lips firmly to his Captain's, moving his hand quickly into Kirk's hair. The hand on his bulge was replaced with a knee, pressing the blonde back onto the bed. Kirk's hands slipped under his First Officer's shirt, tracing over the taut muscle of the Vulcan's chest. Pushing Spock away, Kirk pulled off his own shirt readily, then leaned back on his elbows, gazing up at the brunette through his lashes.

"This was unexpected," Jim quipped, trailing his fingers along the other man's chest, tugging at the hem of his shirt until Spock got the hint and removed it.

"I was under the impression that you appreciated the unexpected, sir," the Vulcan replied, looming over the blonde on his bed, a hand on either side of his head.

"Mm, too true, Spock," the Captain hummed, almost purring under the dominant form of his First Officer. "Feel free to continue this trend."

Spock smirked, lowering his mouth to Jim's jaw and delivering a series of kisses and nips down his neck. With each bite, Kirk let out a small gasp, causing Spock's confidence to grow. He wanted to hear more of those noises, and it was only logical that he do everything in his power to please his Captain.

Lithe fingers worked on Kirk's pants, making a quick job of the fastener. As he de-clothed Kirk's lower half, Spock kissed and licked his way down the man's body, paying special attention to his nipples, drawing delicious keening noises from the blonde. By the time he got to Kirk's groin, the man was a panting mess. 'Just the way I like him,' Spock decided, gazing with hooded eyes at his Captain. Meeting his eyes, Kirk threaded his hands into the Vulcan's always neat hair, quickly ruining it's perfection. Spock licked his lips slowly, teasingly, and breathed lightly on Jim's member.

"I will replace you with Doctor Wallace," Kirk threatened jokingly, tugging at Spock's hair. Taking that as a challenge, the Vulcan drew his tongue over the head, shutting his Captain up immediately with a sharp intake of breath. "_Fuck_, Spock," Kirk hissed, lifting his hips in need. Pressing a hand firmly onto his stomach, the brunette tsked at the man.

"What's the magic word, Captain?" he asked, using a human phrase while pressing a kiss to the base of the weeping cock.

"Spock, you bastard," Kirk complained, tugging his hair.

"Come now, Jim, it's only logical you ask politely," This was accompanied with a lick from base to tip. Kirk whimpered.

"Please, Spock," he begged, breaking down at last, "I need you. Spock, _fuck,_" he drew out the word as a gasp, "_Please!_"

"Well, if you insist, my Captain," Spock conceded, lowering his mouth over the thick member. Despite having never performed this act before, the Vulcan had a fairly good idea of what he was to do. After all, he knew how to bring himself to completion, so he assumed this wouldn't be much different.

Swirling his tongue around the tip, Spock sucked slightly, adoring the needy noises his Captain was making. As he bobbed his head, the brunette hummed, the vibrations causing Kirk to buck his hips involuntarily. The action pushed his cock deeper into Spock's mouth, touching the back of his throat. Startled, the Vulcan continued, taking his Captain's cock far past his lips. Kirk's twitching became more and more pronounced, and his moans louder, as Spock sucked. Soon, the blonde was gripping tighter than ever to his First Officer's hair, letting out a faint cry of "Coming!". Spock, prepared for the event, let the milky substance pour into his mouth, and swallowed so as to not make a mess. It was only logical.

Sitting up, Spock gazed down at his dishevelled Captain, running a hand through his hair.

"Where'd you learn to do that?" Kirk exclaimed, taking the brunette's hand and kissing his wrist. Spock smirked.

"I believe I am what you call, 'naturally talented', sir," the Vulcan replied smugly. Kirk's brow furrowed.

"I'm good too, you know," he pouted.

"Perhaps with women, yes,"

"Hey! I can do men,"

"Prove it," Spock challenged, knowing that the man could not resist the stab at his honour. Kirk pushed the Vulcan back, quickly changing their positions.

"Watch me," Kirk growled, pinning Spock's hands above his head. As he pressed his lips against the Vulcan's once more, a radio message played through the room.

"_Captain to the bridge. I repeat, could the Captain report to the bridge. We are approaching destination_,"

"Damnit!" Kirk groaned, leaning his forehead against the brunette's. "Rain check?

"I do not understand that sentiment,"

"Of course you don't," Kirk sighed, rolling his eyes and getting off the bed to find his clothes. "What I mean is that I'll prove you wrong later,"

"I'm sure you will, Captain," Spock replied, dressing much more collectedly, fixing his hair, and moving to leave. Kirk grabbed his hand as he reached the door. Spock turned to him, taking in his sex mussed hair and generally tousled appearance.

"Tonight," Kirk said.

"May I ask what you mean, Captain?"

"Come to my room tonight and I'll prove it to you," There was a sparkle in his eye as he said this, his gaze travelling over Spock's now concealed body.

"I accept, sir,"

Kirk's face lit up like a child at Christmas.

"It is only logical that I let you return the favour,"

Groaning, the Captain shoved the Vulcan playfully and passed him.

"Tonight, Spock. I mean it,"


	2. Part 2

**AN: I have never had so many people give feedback on one small chapter before. And all those favourites and followers! Damn, you people, you are awesome people. I ALSO have never written a second chapter so fast before. Huh. Maybe there's a correlation. Or I just like writing smut.**

**Either way, I think this is going to be the last chapter just because I don't want to draw things out too much. Yeah, two-shots! Have a lemon, you wonderful readers. You deserve it.**

* * *

Kirk heard the door to his room slide open behind him as he finished his Captain's log for the day, leaving out choice events. As much as he would like to have recorded the happenings for posterity, Jim decided that some things were better left unsaid. Besides, if things went his way tonight, there would be a lot more where that came from for him to remember.

"Captain, it was good of you to decide to spare Khan," came the voice he had had in his head all day. "It would have been unwise to attack a Klingon planet unprovoked,"

Spinning around in his desk chair, Jim levelled his sexiest look on Spock. The Vulcan, in response, raised a single eyebrow.

"Captain?" he asked, posture straight and stiff as always. Kirk puffed out his breath in a huff. Even after what they had done earlier, Spock was still the same as always around him.

"Do you remember why I asked you here tonight, Spock?"

"As I recall, the details of your plan were never announced,"

"I thought it would have been obvious," Jim replied, running a hand through his hair exasperatedly.

"Captain, as your thinking is highly illogical at the best of times, I have a difficult time guessing at your behaviour," his First Officer replied, stepping farther into the room. Just as Kirk was opening his mouth to complain, Spock continued, "Perhaps you would do better to show me your thoughts, Jim." There was that twinkle of mischief in the Vulcan's eye again; the same one that had been there before he had kissed Jim earlier. Feeling heat rushing to his groin, Kirk stood, closing the gap between them with a few strides.

'Thank God he isn't taller than me,' Kirk could not help but think as he balled his fist in Spock's blue shirt and tugged him flush against him. The sparkle in the Science Officer's eye grew more pronounced as Kirk wrapped his free arm around the small of his back. Ignoring it for the moment, mostly for being to caught up in the warmth of the brunette's body against his own, Kirk pressed his lips softly to Spock's. It was a gentle kiss, almost tentative for the Captain, but the Vulcan soon changed that. Nipping his lower lip, Spock slipped his tongue inside the blonde's now open mouth, twining it with Jim's. Caught off guard, Jim let out a small gasp of pleasure, which he chided himself for. He was being way too vocal with the Vulcan.

This kiss was much different than the ones from earlier. Spock was more forceful, hungrier, and Kirk wasn't about to argue with it. This was like nothing he had ever experienced before. Girls were always such soft things, both in body, as well as technique. With Spock, though, there was a harshness that made Jim shiver with need.

The Captain was vaguely aware of his being pushed backwards, and he assumed they were headed towards his bed. Soon, however, he was deposited on the large sofa on the opposite side of his quarters. Gazing questioningly up at Spock, he was given nothing but that sexy half-smile in response. The Vulcan leaned over him, then breathed in his ear, "Do you trust me, Jim?"

"With my life," he answered immediately. Spock laughed, a low, rumbling sound that Kirk felt go straight to his cock, which was already painfully hard.

"Good," The brunette snaked his tongue around Kirk's ear, then nipped the lobe. "Then trust me, my T'hy'la. Close your eyes,"

Jim obeyed, trying to not think of what the term of endearment did to his breathing, and heard the rustling of fabric. Soft, silky material was drawn over his eyes, tightening at the back as it was tied. The blonde squirmed slightly, not used to the complete lack of vision during sexual activities, till Spock's warm hand caressed his face.

"You will be fine, Jim," his First Officer asserted, pressing a kiss to the side of his mouth, "I have read that the retraction of one sense heightens the rest of a human's senses. It seemed only logical that you would receive more pleasure by my cutting off one of yours, and as I want you to be able to _hear my voice_," he purred into Kirk's ear, "_taste my skin_," he traced a finger around Kirk's mouth, "_smell our sex_," he groped Kirk's bulging member through his pants, "and _feel my body on_...and _in __yours_," Jim whimpered with need, "your sight was the only option."

For a moment, all the Captain could hear was fabric being moved, and then he felt hands on his own clothes, tearing at them until they were in shreds on the couch around him. A hand slipped into his, pulling up into a sitting position as Spock sat opposite him on the sofa. Jim could only assume that they were both naked at this point, and was proven to be right as he was tugged forward to land on his First Officer's hard chest. 'Based on where my hand fell, his chest isn't the only thing that's hard,' the Captain couldn't help thinking, running his fingers over the unfamiliar member. Spock breathed quickly, his only response to the touch.

"I believe you mentioned proving me wrong, did you not?" the Vulcan mentioned, his voice sounding more strained than Kirk had ever heard it. He wished he could see Spock's face at that moment, but didn't want to go against the rules he had set up.

"Huh, guess I did," Jim replied, squeezing his cock as he stroked it.

"You don't have to, Captain," Spock said, worry evident in his voice. Kirk couldn't help but smile at the concern, as well as at how un-Spock-like it was.

"You bet I do,"

Uncertain of what he was doing, yet determined to do it well, Kirk lowered his head until he could feel the warmth radiating from the Vulcan's member. It smelt musky, but not unpleasant. Darting out his tongue as a test, licking slowly up the shaft, Jim heard a quiet intake of breath. Wondering if there was something to the blindfold theory, he dipped his mouth over the head of the weeping cock, experimentally swirling his tongue around the tip. A series of small gasps came from above him, spurring him on. He was going to make that Vulcan moan yet.

Taking more into his mouth, Jim continued his ministrations with his hand on the base of Spock's surprisingly long member. What was before small gasps were soon turning into definite sighs and pants of pleasure, but not a moan. Kirk began to hum, as he remembered Spock doing earlier, recalling how it had felt. His pressure on the cock increased, as well as his rhythm, and his free hand slipped forward to press at the Vulcan's entrance. A surprised gasp came from his First Officer, which Kirk took as a good sign. His unpredictability seemed to be appreciated in this instance. After pumping inside with one finger, Jim slipped in a second, sucking hard on Spock's member as he did so. He could hear the breath catch in his partner's throat just before a loud moan of sheer excited pleasure was released.

"Jim," the name came to his ears, breathy. The blonde slowed and pulled back, wondering what was the problem. "I...I would like to...penetrate you," Spock admitted, voice gruff with need. Kirk swallowed, worried once again at his lack of experience with men. Apparently having seen his expression, despite the lack of eyes, Spock kissed him softly, yet passionately. "I will not have you hurt," the Vulcan promised, stroking a hand down Jim's side, caressing over his bum. The Captain shivered, despite himself, as the hand neared his hole, tensing as he felt Spock's finger searching the opening.

"Did you not just do such a thing to me, Jim?" the Vulcan asked softly. Kirk nodded. "And I seemed to enjoy it, did I not?" Another nod. "Then allow me to do this, T'hy'la."

As he spoke, he slowly inserted the finger, stretching Jim. He moved around uncomfortably until Spock brought his other hand to his cock, using the member as a distraction from the initial feeling of being penetrated. Leaning his head against the blonde's, Spock murmured sweet nothings, something Kirk never thought he'd hear in his life, as the finger pumped in and out of the Captain. A second was added soon, stretching him.

"It stings," he admitted, grimacing. Spock hushed him.

"You are James Tiberius Kirk. You have been in countless bar fights, countless gun fights, and even fist fights with me. You have had your entire body bruised at one time and survived. It is only logical that a bit of stinging, compared to everything else you have endured, should be considered as nothing important," the Vulcan told him sternly, sounding like his usual self, despite the situation. Kirk had not noticed the removal of the fingers until he felt something much larger pressed against his entrance.

"Spock, I can't do this," he cried, panicking. Spock sighed and pushed him backwards so he was lying down.

"You can, and will enjoy it, Captain," the Vulcan told him, placing Jim's legs on his shoulders and realigning to his entrance. Spock ran his fingers along the blonde's stomach reassuringly before pressing in. Kirk couldn't help but flinch and whimper at the pain. Tears pricked at his eyes momentarily before he blinked them away.

"Are you alright, Jim?" Spock asked, brushing away a rogue tear that had fallen down his cheek. Kirk nodded fiercely, refusing to be beaten by this. The pain had begun to diminish already, something he was glad for.

The Vulcan pulled out slowly, allowing the blonde to adjust, before thrusting back inside. This continued for a few more thrusts until something was hit inside Jim that he had been previously unaware of. Stars exploded behind his covered eyes, and a startled moan ripped from his throat.

"What was _that_?" he asked, baffled. Spock merely chuckled and pulled out once more. Though they had started out slow, so as to find _that_ spot, Jim assumed, the pace began to pick up. The only sounds in the room were Jim's moans, Spock's grunts, and the slapping of flesh on flesh. After that first time, the Vulcan hit the unknown spot with deadly accuracy every thrust. Jim, now akin to a whimpering puddle, groped for Spock's face and pulled his lips messily against his own. The kiss was sloppy, laboured, and perfect. The brunette's hand began to stroke at his Captain's cock in time with his thrusts until Jim pulled away from the kiss and cried his First Officer's name. Jim came between their chests as Spock thrust twice more before coming himself, deep inside the blonde, with a moan muffled by his biting Jim's shoulder.

Pulling out, Spock let Jim drop his legs, and removed the blindfold. The Captain blinked at the sudden light until his eyes focused on the tousled, flushed, _sexy_ Vulcan above him. He grinned.

"So that's what a dishevelled Spock looks like," he mused, adoring the way the brunette's face scrunched. Jim gripped his face and kissed him firmly. "He looks like perfection,"

The flush on Spock's face increased at the comment, and Jim couldn't help but laugh. The Vulcan lay down on the sofa, wrapping his arms around the blonde and pulling their sweaty bodies together.

"Moaning and blushing in one day, huh Spock?" Kirk continued, unable to resist, "Seems very human of you,"

"I will go back to my own quarters," the Science Officer muttered, eyes closed. Jim smiled.

"Point taken. No teasing after sex,"

"Go to sleep, Jim,"

"What was that you called me earlier?"

"I said sleep,"

"The-la, or something?"

Spock groaned, frustrated.

"T'hy'la, Jim,"

"Okay,"

The two were silent for a few moments until Jim spoke again.

"So what does it mean?"

"To be my T'hy'la is to be my friend, brother, and lover,"

"Oh," Jim said intelligently. "Thanks, Spock,"

"Just go to sleep, Captain,"

Kirk sighed, knowing he was fighting a losing battle. He just wanted to check one more thing first.

"You'll...still be here in the morning, then?"

Spock raised his head and opened his eyes.

"Of course, Jim," he replied seriously, "I will be here for you always,"

"Okay," Spock put his head back down. Jim closed his own eyes, attempting to sleep, but was too strung out on the naked Vulcan beside him.

"Jim, sleep," Spock demanded, not changing positions.

"Okay, but how about a round two?"


End file.
